Steerable endoscope and improved method of insertion

ABSTRACT

A steerable endoscope has an elongated body with a selectively steerable distal portion and an automatically controlled proximal portion. The endoscope body is inserted into a patient and the selectively steerable distal portion is used to select a desired path within the patient&#39;s body. When the endoscope body is advanced, an electronic motion controller operates the automatically controlled proximal portion to assume the selected curve of the selectively steerable distal portion. Another desired path is selected with the selectively steerable distal portion and the endoscope body is advanced again. As the endoscope body is further advanced, the selected curves propagate proximally along the endoscope body, and when the endoscope body is withdrawn proximally, the selected curves propagate distally along the endoscope body. This creates a serpentine motion in the endoscope body that allows it to negotiate tortuous curves along a desired path through, around, and between organs within the body.

CROSS-REFERENCE TO OTHER APPLICATIONS

[0001] The present application is a continuation of U.S. patentapplication Ser. No. 09/790,204 filed Feb. 20, 2001, which claimspriority of U.S. Provisional Patent Application No. Serial No.60/194,140, filed Apr. 3, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates generally to endoscopes andendoscopic medical procedures. More particularly, it relates to a methodand apparatus to facilitate insertion of a flexible endoscope along atortuous path, such as for colonoscopic examination and treatment.

BACKGROUND OF THE INVENTION

[0003] An endoscope is a medical instrument for visualizing the interiorof a patient's body. Endoscopes can be used for a variety of differentdiagnostic and interventional procedures, including colonoscopy,bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

[0004] Colonoscopy is a medical procedure in which a flexible endoscope,or colonoscope, is inserted into a patient's colon for diagnosticexamination and/or surgical treatment of the colon. A standardcolonoscope is typically 135-185 cm in length and 12-13 mm in diameter,and includes a fiberoptic imaging bundle, illumination fibers and one ortwo instrument channels that may also be used for insufflation orirrigation. The colonoscope is inserted via the patient's anus and isadvanced through the colon, allowing direct visual examination of thecolon, the ileocecal valve and portions of the terminal ileum. Insertionof the colonoscope is complicated by the fact that the colon representsa tortuous and convoluted path. Considerable manipulation of thecolonoscope is often necessary to advance the colonoscope through thecolon, making the procedure more difficult and time consuming and addingto the potential for complications, such as intestinal perforation.Steerable colonoscopes have been devised to facilitate selection of thecorrect path though the curves of the colon. However, as the colonoscopeis inserted farther and farther into the colon, it becomes moredifficult to advance the colonoscope along the selected path. At eachturn, the wall of the colon Must maintain the curve in the colonoscope.The colonoscope rubs against the mucosal surface of the colon along theoutside of each turn. Friction and slack in the colonoscope build up ateach turn, making it more and more difficult to advance and withdraw thecolonoscope. In addition, the force against the wall of the colonincreases with the buildup of friction. In cases of extreme tortuosity,it may become impossible to advance the colonoscope all of the waythrough the colon.

[0005] Steerable endoscopes, catheters and insertion devices for medicalexamination or treatment of internal body structures are described inthe following U.S. patents, the disclosures of which are herebyincorporated by reference in their entirety: U.S. Pat. Nos. 4,753,223;5,337,732; 5,662,587; 4,543,090; 5,383,852; 5,487,757 and 5,337,733.

SUMMARY OF THE INVENTION

[0006] In keeping with the foregoing discussion, the present inventiontakes the form of a steerable endoscope for negotiating tortuous pathsthrough a patient's body. The steerable endoscope can be used for avariety of different diagnostic and interventional procedures, includingcolonoscopy, bronchoscopy, thoracoscopy, laparoscopy and videoendoscopy. The steerable endoscope is particularly well suited fornegotiating the tortuous curves encountered when performing acolonoscopy procedure.

[0007] The steerable endoscope has an elongated body with a manually orselectively steerable distal portion and an automatically controlledproximal portion. The selectively steerable distal portion can beselectively steered or bent up to a full 180 degree bend in anydirection. A fiberoptic imaging bundle and one or more illuminationfibers extend through the body from the proximal end to the distal end.Alternatively, the endoscope can be configured as a video endoscope witha miniaturized video camera, such as a CCD camera, which transmitsimages to a video monitor by a transmission cable or by wirelesstransmission. Optionally, the endoscope may include one or twoinstrument channels that may also be used for insufflation orirrigation.

[0008] A proximal handle attached to the elongate body includes anocular for direct viewing and/or for connection to a video camera, aconnection to an illumination source and one or more luer lock fittingsthat are connected to the instrument channels. The handle is connectedto a steering control for selectively steering or bending theselectively steerable distal portion in the desired direction and to anelectronic motion controller for controlling the automaticallycontrolled proximal portion of the endoscope. An axial motion transduceris provided to measure the axial motion of the endoscope body as it isadvanced and withdrawn. Optionally, the endoscope may include a motor orlinear actuator for automatically advancing and withdrawing theendoscope.

[0009] The method of the present invention involves inserting the distalend of the endoscope body into a patient, either through a naturalorifice or through an incision, and steering the selectively steerabledistal portion to select a desired path. When the endoscope body isadvanced, the electronic motion controller operates the automaticallycontrolled proximal portion of the body to assume the selected curve ofthe selectively steerable distal portion. This process i repeated byselecting another desired path with the selectively steerable distalportion and advancing the endoscope body again. As the endoscope body isfurther advanced, the selected curves propagate proximally along theendoscope body. Similarly, when the endoscope body is withdrawnproximally, the selected curves propagate distally along the endoscopebody. This creates a sort of serpentine motion in the endoscope bodythat allows it to negotiate tortuous curves along a desired path throughor around and between organs within the body.

[0010] The method can be used for performing colonoscopy or otherendoscopic procedures, such as bronchoscopy, thoracoscopy, laparoscopyand video endoscopy. In addition, the apparatus and methods of thepresent invention can be used for inserting other types of instruments,such as surgical instruments, catheters or introducers, along a desiredpath within the body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows a prior art colonoscope being employed for acolonoscopic examination of a patient's colon.

[0012]FIG. 2 shows a first embodiment of the steerable endoscope of thepresent invention.

[0013]FIG. 3 shows a second embodiment of the steerable endoscope of thepresent invention.

[0014]FIG. 4 shows a third embodiment of the steerable endoscope of thepresent invention.

[0015]FIG. 5 shows a fourth embodiment of the steerable endoscope of thepresent invention.

[0016]FIG. 6 shows a wire frame model of a section of the body of theendoscope in a neutral or straight position.

[0017]FIG. 7 shows the wire frame model of the endoscope body shown inFIG. 6 passing through a curve in a patient's colon.

[0018] FIGS. 8-13 show the endoscope of the present invention beingemployed for a colonoscopic examination of a patient's colon.

DETAILED DESCRIPTION OF THE INVENTION

[0019]FIG. 1 shows a prior art colonoscope 500 being employed for acolonoscopic examination of a patient's colon C. The colonoscope 500 hasa proximal handle 506 and an elongate body 502 with a steerable distalportion 504. The body 502 of the colonoscope 500 has been lubricated andinserted into the colon C via the patient's anus A. Utilizing thesteerable distal portion 504 for guidance, the body 502 of thecolonoscope 500 has been maneuvered through several turns in thepatient's colon C to the ascending colon G. Typically, this involves aconsiderable amount of manipulation by pushing, pulling and rotating thecolonoscope 500 from the proximal end to advance it through the turns ofthe colon C. After the steerable distal portion 504 has passed, the wallof the colon C maintains the curve in the flexible body 502 of thecolonoscope 500 as it is advanced. Friction develops along the body 502of the colonoscope 500 as it is inserted, particularly at each turn inthe colon C. Because of the friction, when the user attempts to advancethe colonoscope 500, the body 502′ tends to move outward at each curve,pushing against the wall of the colon C, which exacerbates the problemby increasing the friction and making it more difficult to advance thecolonoscope 500. On the other hand, when the colonoscope 500 iswithdrawn, the body 502″ tends to move inward at each curve taking upthe slack that developed when the colonoscope 500 was advanced. When thepatient's colon C is extremely tortuous, the distal end of the body 502becomes unresponsive to the user's manipulations, and eventually it maybecome impossible to advance the colonoscope 500 any farther. Inaddition to the difficulty that it presents to the user, tortuosity ofthe patient's colon also increases the risk of complications, such asintestinal perforation.

[0020]FIG. 2 shows a first embodiment of the steerable endoscope 100 ofthe present invention. The endoscope 100 has an elongate body 102 with amanually or selectively steerable distal portion 104 and anautomatically controlled proximal portion 106. The selectively steerabledistal portion 104 can be selectively steered or bent up to a full 180degree bend in any direction. A fiberoptic imaging bundle 112 and one ormore illumination fibers 114 extend through the body 102 from theproximal end 110 to the distal end 108. Alternatively, the endoscope 100can be configured as a video endoscope with a miniaturized video camera,such as a CCD camera, positioned at the distal end 108 of the endoscopebody 102. The images from the video camera can be transmitted to a videomonitor by a transmission cable or by wireless transmission. Optionally,the body 102 of the endoscope 100 may include one or two instrumentchannels 116, 118 that may also be used for insufflation or irrigation.The body 102 of the endoscope 100 is highly flexible so that it is ableto bend around small diameter curves without buckling or kinking. Whenconfigured for use as a colonoscope, the body 102 of the endoscope 100is typically from 135 to 185 cm in length and approximately 12-13 mm indiameter. The endoscope 100 can be made in a variety of other sizes andconfigurations for other medical and industrial applications.

[0021] A proximal handle 120 is attached to the proximal end 110 of theelongate body 102. The handle 120 includes an ocular 124 connected tothe fiberoptic imaging bundle 112 for direct viewing and/or forconnection to a video camera 126. The handle 120 is connected to anillumination source 128 by an illumination cable 134 that is connectedto or continuous with the illumination fibers 114. A first luer lockfitting, 130 and a second luer lock fitting 132 on the handle 120 areconnected to the instrument channels 116, 118.

[0022] The handle 120 is connected to an electronic motion controller140 by way of a controller cable 136. A steering control 122 isconnected to the electronic motion controller 140 by way of a secondcable 13 M. The steering control 122 allows the user to selectivelysteer or bend the selectively steerable distal portion 104 of the body102 in the desired direction. The steering control 122 may be a joystickcontroller as shown, or other known steering control mechanism. Theelectronic motion controller 140 controls the motion of theautomatically controlled proximal portion 106 of the body 102. Theelectronic motion controller 140 may be implemented using a motioncontrol program running on a microcomputer or using anapplication-specific motion controller. Alternatively, the electronicmotion controller 140 may be implemented using, a neural networkcontroller.

[0023] An axial motion transducer 150 is provided to measure the axialmotion of the endoscope body 102 as it is advanced and withdrawn. Theaxial motion transducer 150 can be made in many possible configurations.By way of example, the axial motion transducer 150 in FIG. 2 isconfigured as a ring 152 that surrounds the body 102 of the endoscope100. The axial motion transducer 150 is attached to a fixed point ofreference, such as the surgical table or the insertion point for theendoscope 100 on the patient's body. As the body 102 of the endoscope100 slides through the axial motion transducer 150, it produces a signalindicative of the axial position of the endoscope body 102 with respectto the fixed point of reference and sends a signal to the electronicmotion controller 140 by telemetry or by a cable (not shown). The axialmotion transducer 150 may use optical, electronic or mechanical means tomeasure the axial position of the endoscope body 102. Other possibleconfigurations for the axial motion transducer 150 are described below.

[0024]FIG. 3 shows a second embodiment of the endoscope 100 of thepresent invention. As in the embodiment of FIG. 2, the endoscope 100 hasan elongate body 102 with a selectively steerable distal portion 104 andan automatically controlled proximal portion 106. The steering control122 is integrated into proximal handle 120 in the form or one or twodials for selectively steering, the selectively steerable distal portion104 of the endoscope 100. Optionally, the electronic motion controller140 may be miniaturized and integrated into proximal handle 120, aswell. In this embodiment, the axial motion transducer 150 is configuredwith a base 154 that is attachable to a fixed point of reference, suchas the surgical table. A first roller 156 and a second roller 158contact the exterior of the endoscope body 102. A multi-turnpotentiometer 160 or other motion transducer is connected to the firstroller 156 to measure the axial motion of the endoscope body 102 and toproduce a signal indicative of the axial position.

[0025] The endoscope 100 may be manually advanced or withdrawn by theuser by grasping the body 102 distal to the axial motion transducer 150.Alternatively, the first roller 156 and/or second roller 158 may beconnected to a motor 162 for automatically advancing and withdrawing thebody 102 of the endoscope 100.

[0026]FIG. 4 shows a third embodiment of the endoscope 100 of thepresent invention, which utilizes an elongated housing 170 to organizeand contain the endoscope 100. The housing 170 has a base 172 with alinear track 174 to guide the body 102 of the endoscope 100. The housing170 may have an axial motion transducer 150′ that is configured as alinear motion transducer integrated into the linear track 174.Alternatively, the housing, 170 may have an axial motion transducer 150″configured similarly to the axial motion transducer 150 in FIG. 2 or 3.The endoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the housing 170. Alternatively, thehousing 170 may include a motor 176 or other linear motion actuator forautomatically advancing and withdrawing the body 102 of the endoscope100. In another alternative configuration, a motor with friction wheels,similar to that described above in connection with FIG. 3, may beintegrated into the axial motion transducer 150″.

[0027]FIG. 5 shows a fourth embodiment of the endoscope 100 of thepresent invention, which utilizes a rotary housing 180 to organize andcontain the endoscope 100. The housing 180 has a base 182 with arotating drum 184 to guide the body 102 of the endoscope 100. Thehousing 180 may have an axial motion transducer 150′″ that is configuredas a potentiometer connected to the pivot axis 186 of the rotating drum184. Alternatively, the housing 180 may have an axial motion transducer150″ configured similarly to the axial motion transducer 150 in FIG. 2or 3. The endoscope 100 may be manually advanced or withdrawn by theuser by grasping the body 102 distal to the housing 180. Alternatively,the housing 180 may include a motor 188 connected to the rotating drum184 for automatically advancing and withdrawing the body 102 of theendoscope 100. In another alternative configuration, a motor withfriction wheels, similar to that described above in connection with FIG.3, may be integrated into the axial motion transducer 150″.

[0028]FIG. 6 shows a wire frame model of a section of the body 102 ofthe endoscope 100 in a neutral or straight position. Most of theinternal structure of the endoscope body 102 has been eliminated in thisdrawing for the sake of clarity. The endoscope body 102 is divided upinto sections 1, 2, 3 . . . 10, etc. The geometry of each section isdefined by four length measurements along the a, b, c and d axes. Forexample, the geometry of section 1 is defined by the four lengthmeasurements l_(1a), l_(1b), l_(1c), l_(1d), and the geometry of section2 is defined by the four length measurements l_(2a), 1 _(2b), l_(2c),l_(2d), etc. Preferably, each of the length measurements is individuallycontrolled by a linear actuator (not shown). The linear actuators mayutilize one of several different operating principles. For example, eachof the linear actuators may be a self-heating NiTi alloy linear actuatoror an electrorheological plastic actuator, or other known mechanical,pneumatic, hydraulic or electromechanical actuator. The geometry of eachsection may be altered using the linear actuators to change the fourlength measurements along the a, b, c and d axes. Preferably, the lengthmeasurements are changed in complementary pairs to selectively bend theendoscope body 102 in a desired direction. For example, to bend theendoscope body 102 in the direction of the a axis, the measurementsl_(1a), l_(2a), l_(3a) . . . l_(10a) would be shortened and themeasurements l_(1b), l_(2b), l_(3b) . . . l_(10b) would be lengthened anequal amount. The amount by which these measurements are changeddetermines the radius of the resultant curve.

[0029] In the selectively steerable distal portion 104 of the endoscopebody 102, the linear actuators that control the a, b, c and d axismeasurements of each section are selectively controlled by the userthrough the steering control 122. Thus, by appropriate control of the a,b, c and d axis measurements, the selectively steerable distal portion104 of the endoscope body 102 can be selectively steered or bent up to afull 180 degrees in any direction.

[0030] In the automatically controlled proximal portion 106, however,the a, b, c and d axis measurements of each section are automaticallycontrolled by the electronic motion controller 140, which uses a curvepropagation method to control the shape of the endoscope body 102. Toexplain how the curve propagation method operates, FIG. 7 shows the wireframe model of a part of the automatically controlled proximal portion106 of the endoscope body 102 shown in FIG. 6 passing, through a curvein a patient's colon C. For simplicity, an example of a two-dimensionalcurve is shown and only the a and b axes will be considered. In athree-dimensional curve all four of the a, b, c and d axes would bebrought into play.

[0031] In FIG. 7, the endoscope body 102 has been maneuvered through thecurve in the colon C with the benefit of the selectively steerabledistal portion 104 (this part of the procedure is explained in moredetail below) and now the automatically controlled proximal portion 106resides in the curve. Sections 1 and 2 are in a relatively straight partof the colon C, therefore l_(1a)=l_(1b) and l_(2a)=l_(2b). However,because sections 3-7 are in the S-shaped curved section, l_(3a)<l_(3b),l_(4a)<l_(4b) and l_(5a)<l_(5b), but l_(6a)>l_(6b), l_(7a)>l_(7b) andl_(8a)>l_(8b). When the endoscope body 102 is advanced distally by oneunit, section 1 moves into the position marked 1′, section 2 moves intothe position previously occupied by section 1, section 3 moves into theposition previously occupied by section 2, etc. The axial motiontransducer 150 produces a signal indicative of the axial position of theendoscope body 102 with respect to a fixed point of reference and sendsthe signal to the electronic motion controller 140, Under control of theelectronic motion controller 140, each time the endoscope body 102advances one unit, each section in the automatically controlled proximalportion 106 is signaled to assume the shape of the section thatpreviously occupied the space that it is now in. Therefore, when theendoscope body 102 is advanced to the position marked 1′, l_(1a)=l_(1b),l_(2a)=l_(2b), l_(3a)=l_(3b), l_(4a)<l_(4b), l_(5a)<l_(5b),l_(6a)<l_(6b), l_(7a)>l_(7b) and l_(8a)>l_(8b), and l_(9a)>l_(9b), whenthe endoscope body 102 is advanced to the position marked 1″,l_(1a)=l_(1b), l_(2a)=l₂, l_(3a)=l_(3b), l_(4a)=l_(4b), l_(5a)<l_(5b),l_(6a)<l_(2b), l_(7a)<l_(7b), l_(8a)>l_(8b), l_(9a)>l_(9b), andl_(10a)>l_(10b). Thus, the S-shaped curve propagates proximally alongthe length of the automatically controlled proximal portion 106 of theendoscope body 102. The S-shaped curve appears to be fixed in space, asthe endoscope body 102 advances distally.

[0032] Similarly, when the endoscope body 102 is withdrawn proximally,each time the endoscope body 102 is moved proximally by one unit, eachsection in the automatically controlled proximal portion 106 is signaledto assume the shape of the section that previously occupied the spacethat it is now in. The S-shaped curve propagates distally along thelength of the automatically controlled proximal portion 106 of theendoscope body 102, and the S-shaped curve appears to be fixed in space,as the endoscope body 102 withdraws proximally.

[0033] Whenever the endoscope body 102 is advanced or withdrawn, theaxial motion transducer 150 detects the change in position and theelectronic motion controller 140 propagates the selected curvesproximally or distally along the automatically controlled proximalportion 106 of the endoscope body 102 to maintain the curves in aspatially fixed position. This allows the endoscope body 102 to movethrough tortuous curves without putting unnecessary force on the wall ofthe colon C.

[0034] FIGS. 8-13 show the endoscope 100 of the present invention beingemployed for a colonoscopic examination of a patient's colon. In FIG. 8,the endoscope body 102 has been lubricated and inserted into thepatient's colon C through the anus A. The distal end 108 of theendoscope body 102 is advanced through the rectum R until the first turnin the colon C is reached, as observed through the ocular 124 or on avideo monitor. To negotiate the turn, the selectively steerable distalportion 104 of the endoscope body 102 is manually steered toward thesigmoid colon S by the user through the steering control 122. Thecontrol signals from the steering control 122 to the selectivelysteerable distal portion 104 are monitored b the electronic y motioncontroller 140. When the correct curve of the selectively steerabledistal portion 104 for advancing the distal end 108 of the endoscopebody 102 into the sigmoid colon S has been selected, the curve is loggedinto the memory of the electronic motion controller 140 as a reference.This step can be performed in a manual mode, in which the user gives acommand to the electronic motion controller 140 to record the selectedcurve, using keyboard commands or voice commands. Alternatively, thisstep can be performed in an automatic mode, in which the user signals tothe electronic motion controller 140 that the desired curve has beenselected by advancing the endoscope body 102 distally.

[0035] Whether operated in manual mode or automatic mode, once thedesired curve has been selected with the selectively steerable distalportion 104, the endoscope body 102 is advanced distally and theselected curve is propagated proximally along the automaticallycontrolled proximal portion 106 of the endoscope body 102 by theelectronic motion controller 140, as described above. The curve remainsfixed in space while the endoscope body 102 is advanced distally throughthe sigmoid colon S. In a particularly tortuous colon, the selectivelysteerable distal portion 104 may have to be steered through multiplecurves to traverse the sigmoid colon S.

[0036] As illustrated in FIG. 9, the user may stop the endoscope 100 atany point for examination or treatment of the mucosal surface or anyother features within the colon C. The selectively steerable distalportion 104 may be steered in any direction to examine the inside of thecolon C. When the user has completed the examination of the sigmoidcolon S, the selectively steerable distal portion 104 is steered in asuperior direction toward the descending colon D. Once the desired curvehas been selected with the selectively steerable distal portion 104, theendoscope body 102 is advanced distally into the descending colon D, andthe second curve as well as the first curve are propagated proximallyalong the automatically controlled proximal portion 106 of the endoscopebody 102, as shown in FIG. 10.

[0037] If, at any time, the user decides that the path taken by theendoscope body 102 needs to be revised or corrected, the endoscope 100may be withdrawn proximally and the electronic motion controller 140commanded to erase the previously selected curve. This can be donemanually using keyboard commands or voice commands or automatically byprogramming the electronic motion controller 140 to go into a revisemode when the endoscope body 102 is withdrawn a certain distance. Therevised or corrected curve is selected using the selectively steerabledistal portion 104, and the endoscope body 102 is advanced as describedbefore.

[0038] The endoscope body 102 is advanced through the descending colon Duntil it reaches the left (splenic) flexure F_(l) of the colon. Here, inmany cases, the endoscope body 102 must negotiate an almost 180 degreehairpin turn. As before, the desired curve is selected using theselectively steerable distal portion 104, and the endoscope body 102 isadvanced distally through the transverse colon T, as shown in FIG. 11.Each of the previously selected curves is propagated proximally alongthe automatically controlled proximal portion 106 of the endoscope body102. The same procedure is followed at the right (hepatic) flexure F_(r)of the colon and the distal end 108 of the endoscope body 102 isadvanced through the ascending colon G to the cecum E, as shown in FIG.12. The cecum E, the ileocecal valve V and the terminal portion of theileum I can be examined from this point using, the selectively steerabledistal portion 104 of the endoscope body 102.

[0039]FIG. 13 shows the endoscope 100 being, withdrawn through the colonC. As the endoscope 100 is withdrawn, the endoscope body 102 follows thepreviously selected curves by propagating the curves distally along theautomatically controlled proximal portion 106, as described above. Atany point, the user may stop the endoscope 100 for examination ortreatment of the mucosal surface or any other features within the colonC using the selectively steerable distal portion 104 of the endoscopebody 102.

[0040] In one preferred method according to the present invention, theelectronic motion controller 140 includes an electronic memory in whichis created a three-dimensional mathematical model of the patient's colonor other anatomy through which the endoscope body 102 is maneuvered. Thethree-dimensional model can be annotated by the operator to record thelocation of anatomical landmarks, lesions, polyps, biopsy samples andother features of interest. The three-dimensional model of the patient'sanatomy can be used to facilitate reinsertion of the endoscope body 102in subsequent procedures. In addition, the annotations can be used toquickly find the location of the features of interest. For example, thethree-dimensional model can be annotated with the location where abiopsy sample was taken during an exploratory endoscopy. The site of thebiopsy sample can be reliably located again in follow-up procedures totrack the progress of a potential disease process and/or to perform atherapeutic procedure at the site.

[0041] In one particularly preferred variation of this method, theelectronic motion controller 140 can be programmed, based on thethree-dimensional model in the electronic memory, so that the endoscopebody 102 will automatically assume the proper shape to follow thedesired path as it is advanced through the patient's anatomy. Inembodiments of the steerable endoscope 100 that are configured forautomatically advancing and withdrawing the endoscope body 102, asdescribed above in connection with FIGS. 3, 4 and 5, the endoscope body102 can be commanded to advance automatically though the patient'sanatomy to the site of a previously noted lesion or other point ofinterest based on the three-dimensional model in the electronic memory.

[0042] Imaging software would allow the three-dimensional model of thepatient's anatomy obtained using the steerable endoscope 100 to beviewed on a computer monitor or the like. This would facilitatecomparisons between the three-dimensional model and images obtained withother imaging modalities, for example fluoroscopy, radiography,ultrasonography, magnetic resonance imaging (MRI), computed tomography(CT scan), electron beam tomography or virtual colonoscopy. Conversely,images from these other imaging modalities can be used to map out anapproximate path or trajectory to facilitate insertion of the endoscopebody 102. In addition, images from other imaging modalities can be usedto facilitate locating suspected lesions with the steerable endoscope100. For example, images obtained using a barium-contrast radiograph ofthe colon can be used to map out an approximate path to facilitateinsertion of the endoscope body 102 into the patient's colon. Thelocation and depth of any suspected lesions seen on the radiograph canbe noted so that the endoscope body 102 can be quickly and reliablyguided to the vicinity of the lesion.

[0043] Imaging modalities that provide three-dimensional information,such as biplanar fluoroscopy, CT or MRI, can be used to program theelectronic motion controller 140 so that the endoscope body 102 willautomatically assume the proper shape to follow the desired path as itis advanced through the patient's anatomy. In embodiments of thesteerable endoscope 100 that are configured for automatically advancingand withdrawing the endoscope body 102, the endoscope body 102 can becommanded to advance automatically though the patient's anatomy alongthe desired path as determined by the three-dimensional imacrinc,information. Similarly, the endoscope body 102 can be commanded toadvance automatically to the site of a suspected lesion or other pointof interest noted on the images.

[0044] Although the endoscope of the present invention has beendescribed for use as a colonoscope, the endoscope can be configured fora number of other medical and industrial applications. In addition, thepresent invention can also be configured as a catheter, cannula,surgical instrument or introducer sheath that uses the principles of theinvention for navigating through tortuous body channels.

[0045] In a variation of the method that is particularly applicable tolaparoscopy or thoracoscopy procedures, the steerable endoscope 100 canbe selectively maneuvered along a desired path around and between organsin a patient's body cavity. The distal end 108 of the endoscope 100 is ginserted into the patient's body cavity through a natural opening,through a surgical incision or through a surgical cannula or introducer.The selectively steerable distal portion 104 can be used to explore andexamine the patient's body cavity and to select a path around andbetween the patient's organs. The electronic motion controller 140 canbe used to control the automatic ally controlled proximal portion 106 ofthe endoscope body 102 to follow the selected path and, if necessary, toreturn to a desired location using the three-dimensional model in theelectronic memory of the electronic motion controller 140.

[0046] While the present invention has been described herein withrespect to the exemplary embodiments and the best mode for practicingthe invention, it will be apparent to one of ordinary skill in the artthat man modifications, improvements and subcombinations of the variousembodiments, adaptations and variations can be made to the inventionwithout departing from the spirit and scope thereof.

I claim:
 1. An apparatus for determining an axial position of anelongate instrument insertable into a body cavity, the elongateinstrument having a proximal portion and a selectively steerable distalportion, the apparatus comprising: a transducer adapted to slidinglyreceive the elongate instrument therethrough while measuring an axialposition of the elongate body during advancement or withdrawal near thetransducer, the transducer being attached to a fixed point of referencerelative to the elongate instrument; and a motion controller inelectrical communication with the transducer for receiving a signal fromthe transducer indicative of the axial position of the elongateinstrument.
 2. The apparatus of claim 1 wherein the transducer isconfigured as a ring which defines an opening through which the elongateinstrument passes.
 3. The apparatus of claim 1 wherein the transducer isadapted to produce a corresponding electrical signal indicative of theaxial position as the elongate instrument passes through the transducer.4. The apparatus of claim 1 further comprising a first roller and asecond roller attached to the transducer for contacting an exteriorsurface of the elongate body.
 5. The apparatus of claim 4 furthercomprising a measurement apparatus in electrical communication with atleast the first roller.
 6. The apparatus of claim 5 wherein themeasurement apparatus comprises a potentiometer.
 7. The apparatus ofclaim 5 further comprising a motor coupled to the first roller forurging the elongate instrument in an axial direction.
 8. The apparatusof claim 1 wherein the transducer is attached adjacently to an elongatedhousing having a base and a linear track upon which the elongate body isadvanced or withdrawn.
 9. The apparatus of claim 1 wherein thetransducer is attached adjacently to a selectively rotatable drum, theelongate body being positionable about a circumference of the drum. 10.The apparatus of claim 9 further comprising a measurement apparatusconnected to a pivot axis of the rotatable drum for converting arotational movement of the drum into a longitudinal translation of theelongate body.
 11. The apparatus of claim 10 wherein the measurementapparatus comprises a potentiometer.
 12. The apparatus of claim 1wherein the transducer measures an axial distance traveled by theelongate instrument by detecting the axial position through a methodselected from the group consisting of optical, electronic, andmechanical methods.
 13. The apparatus of claim 1 wherein the fixed pointof reference comprises a surgical table.
 14. The apparatus of claim 1wherein the fixed point of reference comprises an insertion location ona body of a patient.
 15. The apparatus of claim 1 wherein the transduceris positioned externally of the body cavity.
 16. The apparatus of claim1 wherein the elongate instrument defines at least one lumentherethrough.